In a typical mobile communications environment, a user equipment (UE), including a mobile phone (also known as a cellular or cell phone), a laptop computer with wireless communications capability, or a personal digital assistant (PDA), etc., may communicate voice and/or data signals with one or more service network. The wireless communications between the UE and the service networks may be in compliance with various wireless technologies. A long-term evolution (LTE) system, initiated by the third generation partnership project (3GPP), is now being regarded as a new radio interface and radio network architecture that provides a high data rate, low latency, packet optimization, and improved system capacity and coverage. In the LTE system, a radio access network known as an evolved universal terrestrial radio access network (E-UTRAN) includes a plurality of evolved Node-Bs (eNBs) for communicating with a plurality of user equipments (UEs) and communicates with a core network, Evolved Packet Core (EPC), including a mobility management entity (MME), a serving gateway (SGW), a packet data network gateway (PGW), etc., for NAS (Non Access Stratum) control. A long term evolution-advanced (LTE-A) system, as its name implies, is an evolution of the LTE system and has similar network structure as the LTE system.
In LTE-related systems, Proximity-based Service (ProSe) communication is developed as a technology which allows UEs to directly communicate with each other in close proximity without transmitting/receiving data and/or control signals to the other via an eNB, which means a local or direct path can be used between the UEs. Therefore, in 3GPP LTE spectrum, the operator can move the data path (i.e., user plane) off the access to core networks to direct links between the UEs.
Currently, charging functionality is provided by a user plane node, e.g., a SGW or PGW. However, when the UEs communicate with each other directly via the ProSe communication in a data path and/or a control path, there is no user plane traffic traversing through the user plane node. As a result, the user plane node may not obtain the charging information for the ProSe communication.